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Constant referenced in XML configuration is not defined or cannot be resolved
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<p>
This inspection detects undefined constants in Symfony XML configuration files.
It validates that constants referenced using <code>&lt;argument type="constant"&gt;</code>
are actually defined and available.
</p>

<p>
The inspection checks for:
</p>

<ul>
    <li>Undefined PHP constants in <code>&lt;argument type="constant"&gt;</code> elements</li>
    <li>Constants that don't exist in the current PHP context</li>
    <li>Misspelled constant names</li>
</ul>

<p>
Example XML configuration that would trigger this inspection:
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<pre><code>
&lt;services&gt;
    &lt;service id="my_service" class="App\Service\MyService"&gt;
        &lt;!-- Valid constant references --&gt;
        &lt;argument type="constant"&gt;DateTime::class&lt;/argument&gt;
        &lt;argument type="constant"&gt;PHP_VERSION&lt;/argument&gt;

        &lt;!-- Invalid constant that will trigger inspection --&gt;
        &lt;argument type="constant"&gt;\Foobar\Car::UNDEFINED_CONSTANT&lt;/argument&gt;

        &lt;!-- If MAX_ITEMS doesn't exist on MyService class, this will trigger inspection --&gt;
        &lt;argument type="constant"&gt;App\Service\MyService::MAX_ITEMS&lt;/argument&gt;
    &lt;/service&gt;

    &lt;service id="another_service" class="DateTime"&gt;
        &lt;argument type="constant"&gt;\Foobar\Car::FOOBAR_1&lt;/argument&gt; &lt;!-- This will trigger inspection --&gt;
    &lt;/service&gt;
&lt;/services&gt;
</code></pre>

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